directory: remove directory icon for ..

In directories that contained sub-directories, styling was being applied to the `..` file. This fix makes `..` never receive styling.

I had to consider whether earlier authors intended that `..` receive styling. The code's intent seemed conflicted.

- iconStyle() had a `continue` if the file's name was `..`, suggesting that there shouldn't be styling for it.
- iconStyle() *would* have considered `..` a directory 2 lines later.
- html() considered `..` a directory.

Given that iconStyle() seemed to be explicitly trying to prevent `..` from receiving styling, and that in the latter two points, it seemed that `..` was only being considered a directory as a side effect of avoiding file.stat calls, I decided that `..` should not receive styling. Fixing this was as easy as considering `..` **not** a directory.